Waterproof electric blasting cap



A. L. OLIVER.

WATERPROOF ELECTRIC BLASTING CAP.

APPLICATION FILED FEB 3,1921.

Patented Mar. 7, 1922.

ALBERT 1.. OLIVER, or oAKLAND, cALIro'RNIA, ASSIGNOR '1'0 CALIFORNIA CAP 00M PANY, or OAKLAND, CALIFORNIA, A CORPORATION or CALIFORNIA.

PA e r 0mm.

WATERPROOF ELECTRIC I BLASTING- GAP.

To whom iii may concern.

Be it known that I, ALBERT L. OLIVER, a citlzen of the United States, residing at Oakland, in the county of Alameda and State of California, have invented certain new and useful Improvements in Waten proof Electric Blasting Caps, of which the following is a specification.

The present invention relates to a blasting cap particularly adapted for use in submarine or deep well work, wherein the cap must be maintained water proof and must -necessarily withstand considerable external pressure.

The present invention has for its principal object toprovide a cap of the above is employed and is capable of withstanc ing considerable external pressure, and in which a quantity of fulmlnate of mercury or similar material is deposited, and which is adapted to be electrically exploded, said compound being held within the casing by a multiple layered closure plug constructed and formed in such manner as to prevent the entrance of water or other fluid through the open end of the container and to engage the side walls ofthe interior of the container and hold or retain the compound therein and protect the same against severe external pressure, and also affording a greater resistance to the explosion ofthe compound than that afforded by the con tainer, causing the container to burst adjacent to the compound.

Vith the above mentioned and other objects in view, the invention consists in the "novel construction and combination of parts hereinafter described, illustrated in the ac companying drawings and pointed out in the claims hereto appended; it being understood that various changes in the form,

proportion, size and minor details of construction within the scope of the claims may be resorted to without, departing from the spirit of sacrificing any of the advantages of the invention. I

To more fully comprehend the invention, reference is directed to the accompanying drawings, wherein Fig. 1 is a vertical, central, sectional view of the preferred embodiment of my invention.

Fig. 2 is a detail, sectional view of the sulphur plug for containing the igniting Specification of Letters Patent.

Application filed February 3, 1921. Serial No. 442,257.

paste or compound deposited in a depression therein and adheringto the electric igniting resistance.

' Fig. 3 is a bottom plan view of Fig. 2.

Fig. 4 is a "iew similar to Fig. 1, illustrating a modified form of shell or container.

In the drawings, wherein like characters of reference designate corresponding parts-- the numeral 1 indicates a metallic shell or casing, either of the cast or drawn type, and provided with a bore 2 therein opening at one end of said shell or casing, as in the drawing. The wall surface. of said bore 2 for approximately one-half of its length is threaded or roughened as at 3, Fig. 1, and the remainder of said surface is preferably smooth.

In making my improved cap, a quantity of fulmina-te of mercury or similar material 4: foruse in electric blasting caps is deposited in the base of the bore 2 and the same is preferably'held in position by a plug ofsulphur or similar quick hardening,

material, preferably deposited or inserted as a unit from the open end of the bore 2, and the same mounts the lower ends of electric wires 5 connected'by a resistance 6 which is located in a depression 7 in the .underface of the plug 4.

Adhering to the resistancefi is a body of igniting paste 8 composed of'nitro cellulose,

meal powder, fulminate of mercury or any composition of these or similar materials combined with any suitable adhesive for making a paste readily ignitible by an electrically heated wire. This plug, it will be observed, retains the material 4' within the base of the bore 2, and to quickly retain this plug in position a quantity of hot sulphur 9 is poured into the upper end of the bore 2, and, in solidifying, engages the threads 3 holding the plug and compound 4: in position. This sulphur retainer is relatively brittle when dry and is com aratively weak, so to provide a retaining pug of great resistance to completely fill the diameter of the bore 2 above said sulphur 9, I deposit in a plastic form a layer of litharge and glycerine 10 or other similar cement or compound adapted on hardening to expand and tightly engage with the threads 3 and with the wires 5, which are drawn upwardly Within the upper end of the bore 2. To further provide a water proof closure for the unfilled portion of the bore 2, I deposit in a plastic condition in the upper end of the bore a layer of petro-elastic cement or similar plastic base material 11 adapted to provide a, layer of water proofing above the layer of retaining material, and to finish off the unfilled portion of the bore 2. l deposit a final layer 12 of sulphur.

It will be apparent that the layers 10 and 11 provide respectively a closure plug. tightly engaging the threads 3 for the full diameter of the bore 2 and a layer of water proof material engaging with the threads, the two layers combining to prevent the forcing of the plugs or layers inwardly into the bore by pressure from the open end thereof, and also providing a resistance preventing explosion of the body for blowing said layers out of the open end of said tube and causing a rupture of the lower end of the shell or casing 1.

The modified form in Fig. 4 discloses the upper end of the shell or casing corrugated as at 13 instead of threaded as at 3, said corrugations providing, as do the threads, an uneven surface on the upper portion of the interior wall of the bore 2.

I claim 1. A fluid proof electric blasting cap comprising an elongated tubular non-pliable metallic body open at one end and capable of withstanding considerable external pressure, the bore of said body provided with a continuous uneven surface extending from its open end to approximately its longitudinal center, a fulminating compound within the base of said bore, a plug insertible as a unit within said bore through its openend-and with its lower end in contact with said fulminating compound for retaining the same in position, laminated layers of plastic material deposited within said bore with the lowermost layer resting on said plugfor closing the remainder of said bore, and for retaining said plug therein, each of said layers engaging for its full depth a portion of the uneven surface of the wall of said bore and with each layer in contact with the other to resist opposing pressures within said bore, and electric means carried by said plug and extended into said bore through said closure layers for igniting said fulminating compound.

2. A. fluid proof and pressure resisting electric blasting cap comprising a tubular rigid metallic shell capable of withstanding considerable external pressure, closed at its lower end and open at its upper end, the inner wall surface of said tube being annularly roughened from its open end to approximately its longitudinal center, a fulminating compound within the base of said tube. electric means communicating with said compound and extending exteriorly of said tube through its open end for igniting said fulminating compound, and a plurality of superimposed layers of material for closing the upper end of said tube and each deposited therein in a plastic condition, said layers each for its full depth engaging a portion of said roughened surface, one of said layers adapted for solidifying and expanding within said tube to afford a primary pressure resistant, and a superimposed layer adapted for remaining in a semi-plastic state to afford a fluid proof closure, the interior of said tube being filled to its capacity .and free from fluid or air spaces, whereby the solid content thereof assists in resisting external pressures.

In testimony whereof I have signed my name to thisspecification.

ALBERT L. OLIVER. 

